Household refrigerator air flow control and method

ABSTRACT

A refrigerator having a freezer compartment on top and a fresh food compartment below with an air duct connecting the two compartments. A temperature control system and method of controlling is provided and includes a temperature sensing element located at the top of the fresh food compartment and shielded from the stream of cold air being directed into the fresh food compartment. The temperature sensing element changes the temperature in both the freezer and fresh food compartments without changing the constant ratio of those respective compartment temperatures. An air flow assembly divides the cold air entering the fresh food compartment through the connecting air duct between the top of the compartment and the bottom. The air flow control assembly is arranged to divide the cold air stream such that the ratio of the difference in the freezer and fresh food compartment temperatures is changed. By this air flow system and method, the interaction between the cold air flow control and the temperature sensing element provides that the temperature in the freezer compartment may be adjusted up or down while the fresh food compartment temperature remains relatively constant.

CROSS REFERENCE TO RELATED APPLICATION

This application is a division of copending Pat. Application Ser. No.967,743, filed Dec. 8, 1978, now U.S. Pat. No. 4,229,945, for "HouseholdRefrigerator Air Flow Control and Method" in the names of James R.Griffin and Raymond M. Schreck and assigned to the assignee of thisapplication.

BACKGROUND OF THE INVENTION

This invention relates to household refrigerators and is moreparticularly concerned with a combination refrigerator, that is, arefrigerator including a freezer compartment on top and a fresh foodcompartment below, both of which are cooled by circulation air from thetwo compartments over a single evaporator employing a single fan toaccomplish the circulation. This invention relates to an air flowcontrol and method of controlling the circulation of air to thus controlthe temperature of the refrigerator compartments.

Combination refrigerators, including a single evaporator and a singlefan for circulating air from the freezer and fresh food compartmentsover the evaporator are well known. In the operation of suchrefrigerators, a major portion of the refrigerated air from theevaporator is directed into the freezer compartment while a smallerportion is directed into the fresh food compartment. In addition to thecost advantage resulting from the employment of a single evaporator anda single fan for refrigerating two separate compartments, suchrefrigerators have the additional advantage of permitting automaticdefrost of the evaporator which is normally contained within anevaporator chamber outside of or separate from both of the storagecompartments without significantly disturbing the temperatures of thosecompartments.

Various means have been used or proposed for providing temperaturecontrol employing a single thermostat for maintaining the twocompartments within their desired operating temperature ranges. One suchmeans of control is described in U.S. Pat. No. 3,320,761. Generally,thermostatic control of the evaporator is achieved by using an airtemperature sensing element in the warmer fresh food compartment. Anadjustable air flow divider proportions the flow of air cooled by theevaporator, through the freezer and fresh food compartments, to thusprovide the desired temperature differential between the freezer andfresh food compartments.

The air flow divider is adjusted, however, during a particular ambientatmospheric condition, for example, 70° F., the satisfactory control maynot be achieved at a higher ambient atmospheric temperature, forexample, 100° F., due to the unequal rate of heat flow into the freshfood compartment. In the higher ambient temperatures, the heat flow fromthe ambient into the fresh food compartment is higher relative to thefreezer compartment than in low ambient temperatures. This can beremedied by increasing the ratio of cold air into the food storagecompartment in higher ambients. Such changes in usage conditions may beaccommodated by including a manually-operable fresh food compartment airflow adjustment. One such control system is shown in U.S. Pat. No.3,656,314 wherein there is described an air conduit having branches thatprovide separate cooling air discharge into the freezer compartment andhas a temperature sensing means disposed in the conduit for controllingthe temperature. The temperature sensing means, however, is located inthe cold air stream upstream of a damper that controls the amount ofcold air being introduced into the fresh food compartment. With thisarrangement, the temperature sensing means will give a constant freezercontrol response rather than a constant fresh food response since it ismost heavily biased by freezer air temperature. There is an adjustablecontrol for regulating the amount of cold air passing into the freshfood compartment. However, with such an arrangement, the fresh foodtemperature is inadvertently affected which can result in thetemperature being either too high or too low in the fresh foodcompartment.

It is highly desirable to control the temperature in the refrigerator sothat the temperature in the fresh food compartment stays relativelyconstant and the ratio of the temperatures in the freezer and fresh foodcompartments is changed. By our invention, these desirablecharacteristics of a refrigerator air flow system are provided.

SUMMARY OF THE INVENTION

There is provided in a refrigerator having a freezer compartment on topand a fresh food compartment below the freezer compartment an air flowsystem including an air duct connecting the freezer compartment and thefresh food compartment to introduce a stream of cold air into the freshfood compartment. There is a temperature sensing element located at thetop of the fresh food compartment and shielded from the stream of coldair being directed into the fresh food compartment. This temperaturesensing element is utilized to change the temperature in both thefreezer and fresh food compartments without significantly changing theconstant ratio of those respective compartment temperatures. This may beaccomplished by turning the refrigeration system and fan on and off inresponse to a present temperature calibration of the temperature sensingelement, thereby controlling the total quantity of cold air being madeavailable to the freezer and fresh food compartments. An air flowcontrol assembly is located in the cold air stream and is utilized todivide the cold air entering the fresh food compartment between the topof the compartment and the bottom. The air flow control assemblyincludes a chamber for receiving the stream of cold air and a firstopening for directing a portion of the stream of cold air into the topof the fresh food compartment with a first air passage from the chamberto the first opening. There is also a second opening for directing aportion of the stream of cold air downwardly into the bottom of thefresh food compartment and a second air passage from the chamber to thesecond opening. The assembly has first and second dampers and means forrotating the dampers in unison with the dampers being spaced from eachother such that when the first damper blocks the first air passage, thesecond damper blocks the second air passage. Upon rotation of thedampers, they will divide the cold air stream being directed to thefirst and second openings and change the ratio of the temperature in thefreezer and fresh food compartments. By so doing, the interactionbetween the air flow system and the temperature sensing element allowsthe temperature in the freezer compartment to be adjusted up or downwhile the fresh food temperature remains relatively constant.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevational view of a refrigerator having a freezercompartment on top and a fresh food compartment on the bottom embodyingthe invention.

FIG. 2 is a side elevational view, partly in section, of a refrigeratorcabinet having a freezer compartment on top and a fresh food compartmenton the bottom showing somewhat schematically one form of the presentinvention as embodied herein.

FIG. 3 is a cross sectional view of the air flow control assembly of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to FIGS. 1 and 2 of the drawings, there is illustrated arefrigerator cabinet including an outer case 1, an upper inner liner 2defining a freezer storage compartment 3 and a lower inner liner 4defining a fresh food storage compartment 5. The forward edges of bothliners are spaced from the forward edges of the case 1 and these spacesare bridged by heat insulating breaker strips 6 while the spaces betweenthe liners and the outside case are filled with suitable insulatingmaterial 7. The access openings to the freezer and fresh foodcompartments are respectively closed by doors 8 and 9.

Refrigeration for the two compartments is provided by an evaporator 10positioned in the partition 11 between the two liners 2 and 4 which formpart of the refrigeration system including compressor 12 and a condenser13. A fan 14 rearwardly from the evaporator 10 provides means forcirculating air from the two compartments over the evaporator 10 andback into the compartments.

A temperature control thermostat generally indicated by the numeral 15,including a temperature sensing element 16 (FIG. 3), is provided forautomatically controlling the operation of the compressor 12 to maintainthe temperature within the fresh food compartment within a controlledrange. This thermostat and its cooperation with the other components ofthe air flow control system will be discussed in more detail later.

The evaporator 10 operates at temperatures below freezing and, for thepurpose of periodically removing accumulated frost from the evaporatorsurfaces, there is provided a defrost heater 17 which is periodicallyenergized by operation of a timer 18.

The refrigerator thus far described is similar to that shown anddescribed in U.S. Pat. No. 3,320,761, assigned to the same assignee asthe present invention, and reference is made to that patent for a morecomplete description of the operating components thereof.

In household refrigerators it is often desirable to provide a pan in thefresh food compartment in which fresh meat and the like may be kept andusually at a slightly lower temperature than the rest of the fresh foodcompartment. As shown in FIGS. 1 and 2, there is a meat keeper pan 20located at the bottom of the fresh food compartment 5. The meat keeperpan 20 includes a cover 21 to prevent any circulation of air within thefresh food compartment 5 from tending to dry out the food itemsmaintained in the meat keeper pan 20.

With reference to FIG. 2 in the operation of the refrigerator, the fan14 operates to pull air across the cold evaporator 10 which air entersthe partition 11 upstream of the evaporator 10 from both the freezercompartment 3 and the fresh food compartment 5, as shown by the arrows.The air which is cooled by passing over the evaporator 10 is fan forcedinto the freezer compartment 3. The rear of the freezer compartment hasan opening 22 that allows some of the cold air to flow into an air duct24 connecting the freezer compartment and fresh food compartment. Theair duct 24 has a discharge opening 26 for introducing cold air into thefresh food compartment 5. By our invention, the cold air stream beingdischarged into the fresh food compartment 5 is divided so that aportion of the cold air stream is directed to the top of the fresh foodcompartment and a portion is directed downwardly to the bottom of thefresh food compartment and preferably to an area surrounding the meatkeeper pan 20 since it is desirable that that pan and its contents bekept at a slightly lower temperature than the rest of the fresh foodcompartment. The downwardly directed air flows in an air duct 28 fromthe top of the fresh food compartment to the bottom. The meat keeper pan20 is spaced slightly forwardly of wall 29 that forms a part of air duct28 so that a variable cross-section passageway 31 is provided betweenthe rear wall 29 and it and between the bottom wall 33 and it to leadthe flow of air from the air duct 28 downwardly around and thenforwardly around the meat keeper pan 20 then upwardly within the freshfood compartment 5. By this direct impingement of cold air on the meatkeeper pan 20, the temperature of the meat keeper is maintained at aslightly lower temperature than the remainder of the fresh foodcompartment 5. To divide the stream of cold air being directed into thefresh food compartment, as described above, there is provided an airflow control assembly 30, the operation and function of which will nowbe described.

With reference to FIG. 3, the air flow control assembly 30 is shown incross sectional detail and it is positioned within the fresh foodcompartment 5 in close proximity to the partition 11 dividing thefreezer and fresh food compartments 3 and 5 respectively. The air flowcontrol assembly 30 is secured by any suitable means to the partition 11and the rear wall 35 of the lower inner liner 4. The cold air passingdownwardly through air duct 24 enters the air flow control assembly 30through opening 26 into an air chamber 32. The air flow control assembly30 has a first opening 34 for directing a portion of the stream of coldair into the top of the fresh food compartment. There is a first airpassage 36 from the chamber 32 to the first opening 34. The air flowcontrol assembly 30 also includes a second opening 38 for directing aportion of the stream of cold air downwardly into the bottom of thefresh food compartment and a second air passage 40 from the chamber 32to the second opening 38. The second opening 38 discharges air into theair duct 28 which leads to the bottom of the fresh food compartment 5and particularly to the meat keeper pan 20.

To control the amount of cold air being divided between the firstopening and second opening respectively, there is provided in the airflow control assembly an air flow control having a first damper 42 and asecond damper 44 attached to a rotatable axle 46. The dampers 42 and 44are spaced from each other and are stationarily fixed to the axle 46such that when the first damper 42 blocks the first air passage 36, thesecond damper 44 is in position to block the second air passage 40. Atone end of the axle 46, there is a dial 48 accessible from the interiorof the fresh food compartment 5 to allow an operator to manually rotatethe dial which, in turn, rotates the axle and the attached dampers. Bysuch manual rotation, the amount of air being directed through therespective first and second openings 36 and 38 may be easily controlled.In effect, then, the air flow control operates as a metering device toadjust the amount of cold air being directed to the top of the freshfood compartment and to the bottom of the fresh food compartment. Thefirst opening 34 and passage 36 are larger in dimension than the secondopening 38 and passage 40 so that a larger amount of the cold air willbe discharged into the top of the fresh food compartment relative to thecold air being discharged into the bottom of the fresh food compartment.Generally speaking, the amount of total cold air being dischargedthrough the first opening 34 is approximately two times the amount ofcold air being discharged through the second opening 38.

As mentioned previously, there is provided a thermostat 15 having atemperature sensing element 16 for controlling the temperature of therefrigerator. The temperature sensing element 16 is located above theair flow control assembly 30 and is shielded from the stream of cold airpassage through the first passage 36 and the opening 34. This shieldingis provided by the upper wall 50 of a portion of the first passage 36and an upwardly projecting wall 52 between the upper wall 50 and thepartition 11. Operation of the refrigerating system, including the fan,causes air from both the freezer compartment 3 and the fresh foodcompartment 5 to pass over the cold evaporator 10 and be introduced intothe freezer compartment 3. From the freezer compartment 3, a stream ofcold air is caused to flow into the fresh food compartment 5. The methodof controlling the refrigerator temperature includes locating thetemperature sensing element 16 at the top of the fresh food compartment5 and shielding the temperature sensing element from the stream of coldair being directed into the fresh food compartment. This arrangementallows the thermostat to sense the temperature of a mixture of the freshfood compartment ambient temperature and the temperature of the cold airflowing through the air flow control assembly, and is most heavilybiased by the fresh food compartment temperature. The temperaturesensing element is utilized to control the temperature in both thefreezer and fresh food compartment without significantly changing theconstant ratio of the respective compartment temperatures. That is, bylocating the temperature sensing element at the top of the fresh foodcompartment and shielded from the flow of cold air being introduced inthe fresh food compartment, it will act to control the temperature ofthe freezer by controlling the amount of cold air supplied to thefreezer, but will not affect the ratio of the temperature in the freezercompartment relative to the temperature in the fresh food compartment.By our method of controlling the temperature of the refrigerator, thestream of cold air entering the fresh food compartment is divided intotwo streams, one going to the top of the fresh food compartment--theother going to the bottom of the fresh food compartment. The controlprovides for an equal ratio of the amount of air flowing in the twostreams. That is, if the dial 48 is manually rotated which moves damper42 to reduce the amount of cold air from the chamber 32 through passage36 and first opening 34, the amount of cold air flowing from the chamber32 through passage 40 and second opening 38 will also be proportionallyreduced. Conversely, by moving the dial 48 in the opposite direction,the amount of cold air passing from the chamber 32 through passage 36and the first opening 34 is increased and the amount of cold air passingfrom the chamber 32 through passage 40 and the second opening 38 will beproportionally increased. The cooperation or interaction between thetemperature sensing element 16 and its shielding structural arrangement,together with the proportionate control of the stream of cold air beingdirected to the top and to the bottom of the fresh food compartment,will cause the temperature in the freezer compartment to be eitherraised or lowered and the temperature difference between the fresh foodcompartment temperature and the freezer temperature will be changed sothat the fresh food compartment temperature remains relatively constant.

The foregoing is a description of the preferred embodiment and method ofthe invention and it should be understood that variations may be madethereto without departing from the true spirit of the invention asdefined in the appended claims.

What is claimed is:
 1. The method of controlling the temperature in arefrigerator having a freezer compartment and a fresh food compartmentseparated by a partition comprising:(a) flowing a stream of cold airinto the fresh food compartment, (b) locating a temperature sensingelement at the top of the fresh food compartment, (c) shielding thetemperature sensing element from the stream of cold air being directedinto the fresh food compartment, (d) controlling the temperature in boththe freezer and fresh food compartments without significantly changingthe constant ratio of those respective compartment temperatures byutilizing the temperature sensing element, (e) dividing the stream ofcold air entering the fresh food compartment into two streams, one goingto the top of the fresh food compartment, and the other going to thebottom of the fresh food compartment, and (f) controlling in equal ratiothe amount of air flowing in the two streams to thereby change the ratioof the temperatures in the freezer and fresh food compartments.
 2. Themethod of claim 1 wherein the ratio of the cold air stream going to thetop of the fresh food compartment relative to the stream going to thebottom of the fresh food compartment is approximately two to one.
 3. Themethod of claim 1 wherein the stream of cold air going to the bottom ofthe fresh food compartment is impinged upon a meat keeper pan.
 4. Themethod of claim 1 wherein the freezer compartment is on top and thefresh food compartment is below the freezer compartment.
 5. The methodof claim 1 wherein controlling in equal ratio the amount of air flowingin the two streams is by rotating dampers to cause the air flowing inboth streams to be increased and decreased in equal ratio.
 6. Themethod, according to claim 5, wherein the dampers are fixed to arotatable axle and the rotating is accomplished manually.
 7. The method,according to claim 6, wherein moving a dial accessible from inside thefresh food compartment and connected to the axle is utilized forrotating the dampers.